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Intelligence Testing - nature v nurture
US Army Testing Programme In 1994, the American Psychological Association (APA) established a special task force to produce a report on the 'knowns and unknowns' about human intelligence (Neisser et al., 1996). This commission was as a result of a book published called 'The Bell Curve' which contained controversial claims. The authors claimed that difference in IQ have a strong genetic basis and are therefore fixed and that environmental factors including education make little difference to a person's intellectual ability. They also claimed that there are inherent differences in intelligence between social groups, particularly across class and racial divisions. These differences in intelligence by group were also claimed to be genetic, permanent and unalterable. This poses the question: is intelligence derived by nature or nurture or both? An army testing programme was carried out in 1917-18 by a team of American psychologists led by Robert Yerkes (the then president of the APA). Yerkes introduced intelligence testing into the process of military recruitment to support the war effort. Yerkes believed that he could make the army more effective through psychology. Intelligence tests were developed for the US Army known as 'army mental tests' (Yoakum and Yerkes, 1920). There were two versions of the army mental tests: Alpha and Beta. The Alpha test was for basic reading ability for those with good command of English. The other Beta test was for the rest which involved pictures and numbers rather than words. Yerkes went on to develop National Intelligence Tests with Terman. These were aimed at primary schoolchildren. This became the basis of college recruitment. In 1938, Sir Cyril Burt, an influential figure in British education at the time just like Yerkes and Terman, argued that a child's intellectual development is governed by 'general intelligence' and that intelligence testing at an early age could be used for educational selection. This underpinned the subsequent development of the 11 plus exam. Conclusions of Tests Yerkes had accumulated test data from 1.7m army recruits and decided to analyse this. He drew two broad conclusions: 1. The average intelligence of the population of the US was lower than previously thought 2. The tests revealed a clear hierarchy among social groups Eugenics Movement and interpretation as 'scientific racism' Intelligence measurement was popular with exponents of the 'eugenics movement'. The eugenicists believed that there are innate differences in ability between groups in society. The principles of eugenics were reflected in both of Yerke's conclusions. Alternative interpretation A different interpretation of the results would point to the fact that there was a strong link between the score on the army tests and the amount of schooling a person had received. Diseases associated with poverty were more prevalent among people who scored poorly. This interpretation discredits the eugenics interpretation which may be politically motivated. The results provide evidence that the scores may not have been based on innate intellectual ability but involve environmental factors. Because of the interpretation of Yerkes work, they were used to justify a quota on immigration from certain parts of Eastern and Southern Europe which was passed by the US Congress in 1924. According to Gould, this change in policy marked on of the greatest victories of scientific racism in American history which Yerke and his colleagues helped to bring about. Scientific racism is the manipulation of scientific theories and methods to justify the belief in racial superiority or inferiority. Mainstream psychological research overwhelmingly rejects the notion that there are innate differences in intelligence between racial or ethnic groups. Improvement in intelligence test design Because of the way in which early intelligence tests were interpreted, the design of intelligence tests has improved. This had led to the development of standardisation procedures - a process of establishing a set of test norms which are then used for interpretation of test results.